textproduct: Quad Cities

KEY MESSAGES

- Strong to severe storms are likely (some significant severe possible) through the later afternoon and evening, with highest confidence in coverage along the Highway 20 corridor and lower confidence on the southern extent. We have an Enhanced (level 3/5) Risk for Severe Weather for our north, and Slight Risk (level 2/5) south.

- Widespread showers and storms are expected Wednesday, with multiple rounds possible. Severe weather will be possible again, especially in the afternoon and evening. SPC highlighted the whole area in a Slight Risk (level 2/5) for severe weather.

- A stronger surface low and cold front will work through the region on Friday, bringing along another potential bout of severe weather. SPC currently has much of our area in an Enhanced Risk (level 3/5) for severe weather.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 130 PM CDT Tue Apr 14 2026

An active forecast lies ahead, with current SPC outlooks highlighting areas along/north of Interstate 80 in an Enhanced (level 3/5) Risk for severe weather, with a Slight Risk (level 2/5) south. Features that we are watching as potential points for convective initiation will be subtle outflow boundaries over the area, resulting from overnight convection. Also, we will have a stationary boundary draped over/near our northern counties along Highway 20. This stationary boundary will be the area of most concern, as it will provide the necessary surface forcing for convective initiation. Further, we will see the LLJ increase in magnitude later this afternoon and through the evening, converging near that boundary. Thus, there will be plenty of forcing in our north for thunderstorm potential. We are looking at the potential for discrete supercell storms, where coverage may increase in the evening hours owing to the strengthening LLJ. Below, we will dive into timing and environmental details.

The main forecast challenge lies with the location and timing of convection, owing to the cap in place over the area. Best chances to see storms this afternoon/evening will be along and north of the Highway 20 corridor, where we will see the best forcing to overcome the cap. Although, our whole outlook is highlighted for severe weather for a reason. Even though areas south of the Highway 20 corridor are capped, there are ways in which we can break through that cap. Looking at 12z CAMs, the cap does seem to be a little weaker than initially forecast, where some CAMs are starting to hint at late afternoon storms developing farther south than the Highway 20 corridor. Further, the latest runs of the HRRR and other high-res CAMs are starting to indicate more coverage of potential supercells, especially closer to the I-80 corridor. This is generally showing the possibility of a broken line of supercells moving west to east from mid-afternoon and through the evening. Thus, mesoscale analysis through the afternoon will be crucial, closely monitoring the extent of surface heating, moisture, along with any sources of mesoscale lift. As was mentioned, an outflow boundary from the morning convection can be in play. This has generally set up along the Interstate 80 corridor this morning, which may be a potential source of forcing necessary. This feature has become more diffuse, but still may serve as a point for initiation, especially with a strengthening LLJ. Timing wise, we are generally looking at the potential for storms to develop as early as 3PM and the severe threat lasting until around 10PM. Storms are expected to move west- east through the evening.

Now, let's dive into the environment that we have in place. As was mentioned, initiation will largely be conditional on surface forcing, with best forcing in our north along the stationary front. Along and south of that boundary, the open warm sector is primed for severe convection, with the cap being the limiting factor. We will see deep layer shear around 45-55 KTs. This will couple with instability around 2500-3500+ CAPE, favorable for organized strong/severe convection. The environment is favoring supercell thunderstorms as the main convective mode. The decreased upper level support should help keep these more discrete at least through the afternoon, with a strengthening LLJ late in the afternoon increasing coverage. This CAPE profile is also quite large in the hail growth layer, with midlevel lapse rates of 7.5-8.5 C/km favoring large hail potential, with some very large hail possible. This increased hail potential has been noted by the SPC. Otherwise, while the deep layer shear is moderate-high, much of this will be seen in the lowest 3km, where the best curvature in model hodographs are seen. Thus, strong LLVL shear will also be favorable for tornadoes as well, some of which could be stronger and longer lived. In the end, all hazards are in play, with hail and tornadoes being the primary threat.

A quick look at our 18z sounding would indicate higher instability is in place, with CAPE around 4000+, along with shear nearing 50 KTs. Thus, a supercell environment is in place. Along with that, our lapse rates are around 9.5 just above the cap, which is more than favorable for severe hail, some of which may be significantly severe. Now, as was forecast, a cap does remain in place. Although, it is not a strong cap, with CIN sitting around -50. Any further heating and mesoscale forcing should be able to overcome this cap. This has been hinted in latest runs in CAMs, showing an increased coverage of storms later this afternoon and evening.

Tonight, we will continue to see the potential for showers/storms as the LLJ remains overhead and better forcing aloft moves in. Cloud cover will remain through the night, moderating temperatures in the 60s. While the overall severe threat will be lower overnight, some guidance hints at some wind/hail potential, but confidence is low.

Tomorrow, we will see another chance for severe weather, with a Slight Risk (level 2/5) for the whole area. A similar environment will be in place tomorrow, but a little less on the instability owing to more cloud cover. Although, it will remain sufficient for convection. The main difference tomorrow will be the surface low and associated cold front passing through. Thus, plenty of surface forcing and better upper level support moving in. With such forcing in play, we are expecting more coverage of storms, especially in the afternoon and evening hours. Storm mode looks to be mixed, with initial supercells eventually growing upscale into line segments, with the main line of convection coming with the cold front that evening/night. Overall, with such forcing, the radar presentation tomorrow may look quite messy through the day. Showers/Storms may be possible through the day, but the better severe threat seems to be the afternoon and evening. All hazards will be in play, but hail and wind seem to be the primary threats at this time.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 130 PM CDT Tue Apr 14 2026

Upper wave that brought impacts to the area on Wednesday will have since pushed east of the area on Thursday, with weak upper ridging moving in. With this, we will see a surface high pass through the area, resulting in a quiet weather day. We should be geared to have quite a pleasant day, with temperatures increasing into the 70s, a westerly breeze, and decreasing cloud cover.

This break of quiet weather will be short-lived though, as Thursday night into Friday, strong southwesterly flow sets up ahead of the next shortwave trough. Strong vort max will approach the area Friday afternoon and evening, with a surface low dragging a seasonally strong cold front through the area. Thus, plenty of forcing in play for storms. A brief look at the environment would indicate sufficient shear and instability in place ahead of the front, favorable for organized convection, some of which could be strong to severe. Environment would be favorable for supercell thunderstorms being the initial storm mode, which may be discrete. Although, as the day goes on and the strongest part of the LLJ core moves in ahead of the cold front, upscale growth is likely. This would lead to a QLCS event for the late afternoon and evening on Friday, where all hazards will be possible. Will refrain from further details, as much can change between now and then. SPC also has their eyes on this system, highlighting much of our area in a 15% or 30% risk for severe weather, which equates to a Slight/Enhanced Risk (level 2/3 of 5) for severe weather.

A look ahead to the upcoming weekend shows a drier pattern developing for Saturday and Sunday as upper-level ridging develops to the west. A cold front should bring notably cooler and more seasonal temperatures to the area on the heels of strong, gusty northwest winds. This could bring our first bout of frost/freeze conditions during this growing season, possibly Saturday night, though winds may stay up to limit this to just a freeze potential for parts of the area, while Sunday night could bring about more widespread freeze and frost with lighter winds as high pressure builds in.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1234 PM CDT Tue Apr 14 2026

MVFR ceilings will occur at all sites through the early afternoon. Thunderstorms are possible between 21 and 03 UTC mainly impacting KCID and KDBQ but confidence remains low on the exact location so used a prob30 at both locations with MVFR conditions expected with any storms. Another round of thunderstorms is possible at KCID, KBRL and KMLI after 06 UTC and and used a prob30 at both locations to account for that. Winds will be south to southwesterly through the period with speeds of 10 to 20 knots and gusts up to 25 to 30 knots this afternoon into the early evening. Winds will diminish after 00 UTC Wednesday.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.